Classifications

• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07D—HETEROCYCLIC COMPOUNDS
  • C07D401/00—Heterocyclic compounds containing two or more hetero rings, having nitrogen atoms as the only ring hetero atoms, at least one ring being a six-membered ring with only one nitrogen atom
  • C07D401/02—Heterocyclic compounds containing two or more hetero rings, having nitrogen atoms as the only ring hetero atoms, at least one ring being a six-membered ring with only one nitrogen atom containing two hetero rings
  • C07D401/12—Heterocyclic compounds containing two or more hetero rings, having nitrogen atoms as the only ring hetero atoms, at least one ring being a six-membered ring with only one nitrogen atom containing two hetero rings linked by a chain containing hetero atoms as chain links
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61P—SPECIFIC THERAPEUTIC ACTIVITY OF CHEMICAL COMPOUNDS OR MEDICINAL PREPARATIONS
  • A61P1/00—Drugs for disorders of the alimentary tract or the digestive system
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61P—SPECIFIC THERAPEUTIC ACTIVITY OF CHEMICAL COMPOUNDS OR MEDICINAL PREPARATIONS
  • A61P1/00—Drugs for disorders of the alimentary tract or the digestive system
  • A61P1/04—Drugs for disorders of the alimentary tract or the digestive system for ulcers, gastritis or reflux esophagitis, e.g. antacids, inhibitors of acid secretion, mucosal protectants

Definitions

• This invention relates to omeprazole and lansoprazole, and more particularly to novel synthetic methods for their preparation.
• Omeprazole which has the chemical structural formula: ##STR1## is a known gastric acid secretion inhibiting agent, and is prescribed clinically for the prevention and treatment of gastrointestinal inflammatory diseases in mammals including man, for example gastritis, gastric ulcer and duodenal ulcer.
• Lansoprazole, which has the chemical structural formula: ##STR2## has similar pharmaceutical activity and medicinal uses.
• omeprazole basically involve the synthesis of the corresponding thioether compound, of the formula: ##STR3## and its subsequent oxidation to the sulfinyl or sulfoxy compound, omeprazole, by various methods such as reaction with hydrogen peroxide over a vanadium compound catalyst (Canadian Patent 1,263,119 Takeda), reaction with peracids, peresters, ozone, etc. (Canadian patent 1,127,158).
• Lansoprazole similarly is produced by oxidation of the thioether compound of formula: ##STR4##
• There are certain disadvantages associated with these processes largely derived from the nature of the thioether (or sulfide) compound being oxidized.
• amide analogues of the thioether compounds A and B i.e. compounds meeting the general formula: ##STR5## can be readily oxidized to the corresponding sulfinyl compounds. Then the sulfinyl compounds can by hydrolysed in alkaline medium to the corresponding carboxylic acid salts which can be decarboxylated to omeprazole or lansoprazole, as the case may be.
• the amide compounds which are subjected to the oxidation step are crystalline solids, as opposed to oils, so that they are readily purified to a high degree of purity by relatively simply precipitation, crystallization and washing procedures.
• the carboxylates and carboxylic acid salts which are formed in the next synthetic step after oxidation are water soluble, whereas the final products, omeprazole and lansoprazole, are not. Accordingly, any unreacted residues of these compounds and many other minor impurities in the final products are simply removable by an aqueous washing procedure.
• Another significant advantage derived from the process of the present invention is in the avoidance of significant discolouration of the product.
• mildly acidic conditions are usually required, and a red discolouration of the product is very difficult to avoid.
• interaction of the nitrogen group on the pyridine ring with the S--C--N grouping involving the azole--thioether linkage occurs, creating a conjugated system.
• Such a conjugated system of S and N atoms would be expected to be highly coloured.
• the amide compound appears to be unique in the combination of its ability to undergo oxidation from the thioether to the sulfinyl compound, and in its relative ease of subsequent hydrolysis to carboxylate.
• Analogous thioether compounds substituted at the same positions with other carbonyl groups, for example--COO--lower alkyl, or with a nitrile group do not oxidize to sulfinyl, at least under acceptable, practical conditions.
• the fact that the amide compound according to the invention, following oxidation, can itself be hydrolysed readily to carboxylic acid or salt is surprising in itself. Normally such hydrolyses of compounds of this nature are extremely difficult, if no impossible, to conduct. In the present case, however, substantially complete hydrolysis is achieved, on heating with an aqueous alkali such as sodium hydroxide, in a time of about three hours.
• X is an alkali metal
• Y is hydrogen or a metal
• X and Y together represent a divalent alkaline earth metal
• oxidation of the amide of general formula II can be conducted using a wide variety of oxidizing agents, such as those previously proposed for use in oxidizing thioether compounds of formula A in the synthesis of omeprazole. These include the use of hydrogen peroxide as oxidizing agent (with or without catalysts).
• oxidizing agents which can be used include peracids, permanganates, tris(trimethyl) peroxide, N-bromo(chloro)succinimide, 1,3-dibromo-5,5-dimethylhydantoin, 2-hydroperoxyhexafluoro-2-propanol, iodosyl benzene, manganese (III) acetylacetonate, oxygen (with or without a catalyst), peroxy monosulfate, ruthenium tetroxide, perborate, periodate, acyl nitrates, t-butylhydroperoxide, dimethyl dioxiranes, hypochlorite, cerium ammonium nitrate, 2-nitrobenzenesulfinyl chloride/potassium superoxide, N-sulfonyloxaziridines, sodium bromite and benzoyl peroxide etc.
• the oxidation is suitably conducted in an aqueous or polar organic solvent medium, depending upon the choice of oxidizing reagents, and under other conditions such as temperatures and pressures commonly used in organic synthesis when working with the chosen oxidation system.
• the oxidation process normally leads to the formation of a mixture of the two diastereomers, reflecting the different configuration around the sulphur group. It is unnecessary to separate these isomers.
• oxidation systems particularly preferred among the oxidation systems is the use of hydrogen peroxide with an organic vanadium compound as catalyst, such as vanadyl bis(acetylacetonate), which gives particularly high yields of sulfinyl compound, in relatively short periods of time.
• an organic vanadium compound such as vanadyl bis(acetylacetonate)
• the starting amide material of formula II and the amide-sulfoxide of formula IV and the carboxylate salts of formula III are all solid, crystallizable compounds, so that they can be readily precipitated from solution for ease of purification by simple washing procedures.
• the oxidation process is a smooth, clean reaction of one crystalline solid to an isolatable stable sulfoxide, as a mixture of diastereoisomers without the use of acid likely to cause degradation and without significant risk of over-oxidation to lead to discolouration.
• the sulfoxides (sulfinyl compounds) so formed are surprisingly stable.
• the sulfinyl-amide compound of formula II is next subjected to hydrolysis, to form the corresponding carboxylic acid salt.
• hydrolysis to form the corresponding carboxylic acid salt.
• an aqueous alkali suitably sodium hydroxide solution
• the salt form can be isolated and used in the decarboxylation step or it can be converted in situ.
• the salt is a solid at ordinary temperatures, so that recovery and purification is relatively easy and straightforward. It is water soluble. Following the recovery of the salt, it can be heated in solution to effect decarboxylation and formation of omeprazole or lansoprazole, as the case may be.
• the salt is not isolated but is warmed in situ in a solvent medium in which it is soluble but in which the product, omeprazole or lansoprazole, is not. The product as it is formed crystallizes out. These final compounds are insoluble in water.
• the end product omeprazole or lansoprazole produced by the process of the present invention is easily and simply purified from the residual, unreacted salt, inorganic by-products and other minor by-products by a washing procedure.
• the desired end products are insoluble in water and lower alkanol solvents, whereas the starting materials and by-products are soluble therein. Consequently, solvent extractions, filtrations and washings are all the steps that are necessary to obtain the end products in highly purified form.
• reaction of the appropriately substituted 2-halo-mercapto-benzimidazole with the appropriately substituted 2-methyl-amido-pyridine thus: ##STR9##
• reaction of the appropriately substituted 2 -pyridine carboxylate with appropriately substituted 2 -S, S-bis(benzimidazole), followed by reaction with ammonia thus: ##STR10##
• reaction of the appropriately substituted 2-halo-pyridine with the appropriately substituted 2-(methylcarboxylate) - thio-benzimidazole followed by treatment with ammonia thus: ##STR11##
• reaction of the appropriately substituted 2-halomethyl-amido-pyridine with the appropriately substituted 2-mercapto-benzimidazole thus: ##STR12##
• reaction of the appropriately substituted 2-mercaptomethyl-amido pyridine with the appropriately substituted 2-halo-benzimidazole thus:
• Omeprazole was produced from 2-(5'-methoxy-2-benzimidazolylsulfinyl)-2-(3,5-dimethyl-4-methoxypyridyl) acetic acid dipotassium salt substrate, as follows:
• 1.0g of substrate was dissolved in 1.0 ml water and mixed with 10 ml of a bisulfite solution pH 4.8, which was prepared by combining 5.0gm of sodium metabisulfite with 75 ml water and 25 ml of methanol.
• the pH of the total reaction mixture was 7.2.
• 35 drops of glacial acetic acid were added from a disposable pipette, bringing the pH to 4.8. Vigorous gas evolution was observed and the solution became cloudy, then oily.
• 2.0 ml of methanol was added and the mixture seeded with omeprazole; solid began to precipitate. The reaction was allowed to proceed for 30 minutes. The solid was filtered, washed with water, and then some acetone. Drying gave 0.45 g of off-white omeprazole free of any substantial impurities.

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• Organic Chemistry (AREA)
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• Nuclear Medicine, Radiotherapy & Molecular Imaging (AREA)
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• 1993
  • 1993-11-04 US US08/145,572 patent/US5374730A/en not_active Expired - Fee Related
• 1994
  • 1994-07-18 US US08/276,378 patent/US5470983A/en not_active Expired - Fee Related
  • 1994-08-17 JP JP7512922A patent/JP2966097B2/ja not_active Expired - Fee Related
  • 1994-08-17 AT AT94924662T patent/ATE206707T1/de not_active IP Right Cessation
  • 1994-08-17 DE DE69428595T patent/DE69428595D1/de not_active Expired - Lifetime
  • 1994-08-17 EP EP94924662A patent/EP0724582B1/de not_active Expired - Lifetime
  • 1994-08-17 WO PCT/CA1994/000452 patent/WO1995012590A1/en active IP Right Grant
  • 1994-08-17 AU AU74875/94A patent/AU7487594A/en not_active Abandoned
  • 1994-08-17 CA CA002170250A patent/CA2170250C/en not_active Expired - Fee Related

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